Operation Dewey Canyon – Sappers Attack Marines on FSB Cunningham

By Michael R. Conroy – All photos were obtained on the internet and inserted into this article by John Podlaski.

The mission of Operation Dewey Canyon was clear — disrupt and destroy enemy logistics in the A Shau Valley, particularly in the NVA’s Base Area 611. As described by Samuel Lipsman and Edward Doyle in Fighting for Time, part of Boston Publishing Company’s multivolume Vietnam Experience, Base Area 611 “straddled the Vietnamese-Laotian border just north of the A Shau Valley and south of the Da Drong River….More than three-quarters of the base area was believed to lie in Laos, along Route 922. This route later joined Route 548 to provide easy access for the NVA into the Da Nang-Hue coastal region.”

NVA engineering units, inactive for months, had reopened several major infiltration routes. This included increased enemy activity along Route 922 as it enters the A Shau Valley in the Republic of South Vietnam from Laos. The intelligence reports brought additional scrutiny on the border areas. Enemy forces laid down heavy volumes of anti-aircraft fire against U.S. Helicopters and other responding high-performance reconnaissance aircraft. Surveillance reported sightings of sophisticated wire communications networks and major engineering works throughout Base Camp Area.611 with, at times, more than 1,000 trucks per day on the move south.Evidence strongly indicated that major elements of the 6th and 9th NVA regiments were attempting to work their way eastward through the A Shau Valley. There they could be reinforced by three battalions of the 812th Regiment, which after the Tet Offensive of 1968 had pulled back into the jungle sanctuary on the border for resupply and infusion of replacements, and by elements of the 4th and 5th NVA regiments, which had withdrawn into the A Shau Valley and Laos under constant U.S. and ARVN pressure during 1968..It seemed obvious that the NVA intended to launch a Tet offensive of some kind in 1969, although probably not of the devastating magnitude of the 1968 Tet. Any form of victory, even one of minor or only temporary tactical value, could have a significant influence upon the civilian population of South Vietnam and the United States, with a more far-reaching effect upon bargaining positions at the Paris peace talks then underway. The enemy’s jungle logistics system would therefore have to be destroyed before it could be used.No longer content to simply hold ground and fight insurgent forces within South Vietnam, U.S. commanders decided that it was time to take the battle to the North Vietnamese Army. To address the threat of a North Vietnamese invasion from Laos they would strike at NVA headquarters and logistics elements in the border areas, thereby denying the enemy access into the critical populated areas of the coastal lowlands of Quang Tri, Thua Thien and Quang Nam provinces.. General Raymond G. DavisGeneral Creighton Abrams, the MACV commander, wanted an operation to be conducted during the winter period of 1968-69, believing that it had great tactical promise in advancing the issues of the war. General Raymond G. Davis, the 3rd Marine Division commander, had discussed such an operation with General Richard Stilwell, XXIV Corps commander..It would not be easy, for the enemy had chosen the site of their base camp well. The terrain in the A Shau Valley was as inhospitable and formidable as any in Vietnam.Because of its experience operating in the rugged mountains and thick jungle canopy of western Quang Tri province, the U.S. 9th Marine Regiment was selected to conduct Operation Dewey Canyon. The men of the regiment were mentally and physically prepared for the rigors of Dewey Canyon’s terrain. They brought to the operation experience in jungle survival and landing zone construction, as well as skills in the conduct of mountain warfare, including heliborne operations and the fire support base concept.During the five-day planning period allowed for the operation, an XM-3 Airborne Personnel Detector picked up evidence of enemy troop concentrations atop a 2,100-foot-long ridgeline 4 1/2 miles from the Laotian border which would be developed into Fire Support Base Cunningham, the eventual command center for the operation.Phase One of the operation, including all pre-D-day activities dealing with getting the artillery support established in the area, began with the opening of three fire support bases (Henderson, Tun Tavern and Shiloh) on January 19.

After the area had been mostly cleared by aviation ordnance, Company I, 3rd Battalion, 9th Marines (I/3/9), and Company M, 3rd Battalion, 9th Marines (M/3/9), conducted heliborne assaults into landing zones (LZs) India and Mike 1700 meters apart on Co Ca Va Ridge. This is a boomerang-shaped ridge approximately a half-mile long, running linearly east to west, with its southern flank an almost sheer cliff to the valley below. Meeting no resistance, the way was clear for Company K, 3rd Battalion, 9th Marines, and engineers to sweep in and begin construction of the fire support base.

DEFENSE DEPT PHOTO (MARINE CORPS) A192845

There was no secrecy involved in the creation of a fire support base. It was an anthill of activity, a major engineering feat and the scene of massive organized confusion as chain saws bit into the huge jungle hardwoods. Numerous explosions sent rocks, splinters, tree limbs, even whole trees, raining down through clouds of choking, rising dust.

The rapid buildup of support facilities at FSB Cunningham was impressive, essentially turning the fire support base into a mini–combat base. When placed atop a dominant terrain feature, the fire support bases were defensible but, as “fixed” forward positions established in the enemy’s territory by forceable entry, they were beacons and targets quickly placed under constant observation by the enemy.

From the moment the Marines landed on Co Ca Va Ridge and began their construction efforts they were under constant enemy surveillance. It was soon obvious to the NVA observers that this was the operational command center for all Marine operations in the area. Accordingly, an NVA sapper unit was ordered to do a feasibility study upon which to formulate assault plans against the fire support base.

DEFENSE DEPT PHOTO (MARINE CORPS) A192682

The Marines knew the enemy’s tactics well. Accordingly, the infantry dug their fighting holes, usually two-man positions, no more than 50 feet apart. As much barbed wire as could be obtained was strung in several different configurations all around the outpost, with additional barriers, such as flares, trip-wire booby traps and anti-personnel mines, placed at what were perceived to be the most likely avenues of enemy approach.

Interlocking fields of fire for individual and crew-served weapons were established so that the defenders achieved a 360-degree integrated pattern of defensive fire. Outposts with good vantage points were established. Listening posts were also established that would intercept attacks or attempts at infiltration before allowing enemy forces to approach close to the defensive lines. Because of their forward and exposed natures, the location of those outposts was continually changing. Additional protection for the fire support base was provided by constant patrols around the position.

The fire support base in no way resembled a secure area with all the trappings of a permanent installation. As operations proceeded, empty ammunition crates were broken down and utilized as footpaths. Garbage disposal, although a problem, was never a high priority. Plastic and cardboard wrappings, expended artillery shells and empty C-ration cans quickly stacked up. Due to the proximity of large stores of ammunition, engineering explosives and powder charges, trash fires were not allowed. The trash pits and bunkers were almost immediately infested with legions of mice and rats.

DEFENSE DEPT PHOTO (MARINE CORPS) A800573

The bunkers were dark and musty. Beds were made of whatever could be scrounged or improvised. There were no windows. Available electricity was reserved for communications and equipment. New men soon learned that peanut butter, when burned, made a dim candle. Inside the bunkers the men attracted hordes of voracious gnats and mosquitoes. Insect bites became ulcerated wounds constantly irritated by salty sweat. Every sore turned into jungle rot.

Mail was infrequently delivered. Hot meals were a thing of the past. Supplies were low and, for several days at a time, nonexistent. The men found themselves eating cold C-ration spaghetti for breakfast and being thankful to have it. There was little water for cooking or shaving and not much more for drinking.

Then there was the constant enemy fire. There was nothing routine about being on the receiving end of an artillery barrage, even when the attacks came daily or hourly and there were no casualties. Nerves were constantly frayed. Marines in underground positions held their breath and cast nervous eyes to straining timbers as loose dirt sifted through their accumulation of timbers, runway matting, sandbags and logs overhead. Equipment was damaged and efficiency impaired. The effect was cumulatively debilitating.

DEFENSE DEPT PHOTO (MARINE CORPS) A192685

Finally, there was the danger of ground attack. A sapper unit of the NVA 812th Regiment had been assigned the mission of attacking FSB Cunningham. Its primary objective was to penetrate the Marine defenses and inflict maximum casualties, destroy equipment, ordnance and installations, and then withdraw. A sapper attack was not designed to seize and hold or occupy a prominent terrain feature.

The sappers took the time to professionally and skillfully plan their attack. A week was devoted to executing a detailed reconnaissance of the fire support base. The terrain was minutely analyzed, defensive patrol patterns studied, crew-served weapons’ positions plotted, obstacles sketched and estimates made of the time that would be required to breach defensive barriers.

DEFENSE DEPT PHOTO (MARINE CORPS) A800583

By February 16, 1969, the NVA sappers were ready to commence their attacks on FSB Cunningham. The period between their final reconnaissance and the commencement of their attack was allocated to briefings and rehearsals. Sand tables had been prepared from detailed sketches made of all the Marine installations. All possible approach routes had been carefully reviewed and the concept of terrain appreciation utilized in developing the plan of attack. The natural and man-made obstacles had been plotted. The Marines’ flares and detonation devices had been located. Each sapper was given precise instructions on his mission. Supporting fire concentrations had been planned, checked and rechecked. The attack signals, passwords, and withdrawal and rally point signals were memorized by all hands. The sappers used a flare system as a source of communications: red — area hard to get into; white — withdrawal; green — victory; green followed by white — reinforcements requested. Personnel, ammunition and weapons were carefully checked.

The sappers were organized into five groups. Group 1, led by Comrade An, consisted of 16 men divided into four-man teams. The first team was assigned to attack the command operations center and mortar positions. The second team was to attack to the right and link up with Comrade Bong’s Group 2 at the helicopter landing zone. The third team was to attack to the left, assault through the landing zone and link up with Group 3, led by Comrade Tan. The fourth team was to attack to the front toward the landing zone.

Group 2 consisted of 15 men divided into four teams led by Comrade Bong. His first four-man team was assigned to attack and destroy the artillery fire direction control center and other battery facilities on the east end of the fire support base. The second team was to attack artillery positions to the right while the third four-man team attacked artillery positions to the left. The remaining three-man team was designated the group’s reserve force.

Comrade Tam’s Group 3 consisted of 12 men divided into four three-man teams concentrating on the west end of the fire support base. The first team was assigned to attack artillery positions to the left. The second team was to attack to the right, advancing and exploiting contact with the Group 1 leader, Comrade An. The third team was to attack directly forward and then link up with a fourth group, led by Comrade Pha, for the mop-up operations. The fourth team would be held in reserve.

Pha’s group was organized to function as the extraction force to assist in the withdrawal of the groups assaulting specific objectives. A fifth group of over 100 men would provide the assaulting forces with a base of fire utilizing RPGs, mortars, automatic weapons and small-arms fire.

The attack forces moved out from their various base camps at 7:30 a.m. Using previously reconned routes, they executed a covered approach to their final assembly areas. Movement as initiated many hours prior to the assault phase as the sappers had deliberately chosen the most difficult avenues of approach to the target in order to avoid observation.

By 6 p.m. all the NVA sapper groups were only 100 meters outside the concertina-wire obstacles surrounding FSB Cunningham. The NVA sappers slowly crept to assault positions just outside the defensive wire, aided by reduced visibility. There was little moonlight and a thick blanket of fog enveloped not only the fire support base but all routes of entry to it. Although the approach was slow and cautious, the assault itself would be made with utmost speed. The sappers assumed that the majority of the defenders would be driven into their bunkers by the mortar attack that would precede their assault. The sappers knew that once the defensive obstacles were breached under this covering fire, the bunkers would become death traps for the Marines.

In anticipation of the Lunar New Year (or Tet) cease-fire, the roaring of the big artillery pieces on FSB Cunningham fell silent at midnight, although the allied countrywide 24-hour truce went into effect at 6 p.m. on February 16.

At precisely 2 a.m., the NVA mortar sections commenced placing accurate supporting fire on previously plotted primary targets, mortar positions, the command bunker, artillery positions and communications bunkers. The Marines could hear the mortar rounds as they were tubed. The devastatingly accurate mortar fire forced the Marines into their bunkers where they felt safe due to a minimum overhead cover of at least four layers of sandbags.

n the midst of the noise, damage and confusion, it was immediately obvious that key installations were the target of the intense barrage. The Marines in fighting holes on the perimeter kept their heads down.

The Marine defensive positions were manned on the northern slope by the men of Lima Company, 3rd Battalion, 9th Marine Regiment (L/3/9). Defensive positions on the flanks and along the southern edge of the ridge were manned by a combination of Marines from the artillery units and Colonel Barrow’s headquarters group. In addition, a reaction force of 50 Marines from the communications, engineer and staff sections of the headquarters group were on standby as a reserve defensive force.

The mortar barrage reached a crescendo at 2:15 a.m. as the NVA assault groups began their efforts to breach the defensive obstacles. The initial assault wave came from the northeast. The sappers made liberal use of bangalore torpedoes fashioned from half-pound blocks of TNT lashed together between bamboo sticks. The ingenious attack route lay through one of the many trash dumps with well-worn paths leading to every major battery facility.

Mats, brush and other local materials were thrown across the barbed wire obstacles. As the mortar fire was lifted, rocket-propelled Chicom grenades, satchel charges and the bangalore torpedoes created the impression that the mortars were still firing, serving to keep the defenders on the perimeter positions inside their bunkers. The Marines were suffering from too many head-ringing explosions to notice the difference. For hours before the cease-fire began, the artillery batteries at the fire support bases had been hammering away in direct support of other defensive positions. The cacophony of noise was deafening. The NVA sappers who broke through the defensive wire barriers tossed concussion grenades and satchel charges into every open hole they could find. The RPGs and automatic weapons fire of the NVA base group was concentrated on the firing slits and ports of the bunkers. Although the situation was confusing, the Marines quickly realized that they were under ground attack and responded ferociously, organizing an effort to clear the base in the face of heavy enemy mortar and recoilless rifle fire.

The sapper attack was an unforgettable experience for navy Lt. Cmdr. (chaplain) David Brock, who later told the division chaplain: “During the early moments of the attack, an NVA soldier stuck his head into the tent where I and two others were rising, but fortunately, did not throw a grenade inside. A grenade was thrown into a small bunker a few feet away, killing two men.”

Chaplain Brock remembers: “The firefight lasted until almost 7:45 a.m. and during this time I stayed with the doctor in the Aid Station in order to administer last rites and to help with the wounded. For two hours it looked as if the Aid Station would be made a last stand. During the firefight various thoughts went through my mind, such as: Would we live through this? Will the men be able to hold out? How were the young men on the lines doing? I must admit that I was scared but the feeling soon passed because we were too busy. The others were afraid too but not one of them showed his fear. As a matter of fact, it warmed one’s heart to see just how well these young men did in the face of death.”

Lieutenant Commander Brock was one of the regiment’s rather unique lot of chaplains, who almost seemed as if they were handpicked to serve with this particular group of hardnosed Marines. Brock had seen action in the European Theatre of Operations as a U.S. Army sergeant in World War II. He earned a Navy Commendation Medal with combat “V” and a Vietnamese Cross of Gallantry with a Silver Star in Vietnam.

The officer in charge of the fire support base was partially buried in a caved-in bunker during the mortar attack. As he crawled out, he came face to face with one of the sappers. The Marine had a grenade in his hand but was too close to the enemy soldier to use it. He leaped on the surprised enemy soldier and bludgeoned him to death with the heavy base of the grenade.

Using his personal knife as his primary weapon, the company gunnery sergeant killed several of the sappers in hand-to-hand combat. Marines from the 106mm battery, who had manned a machine gun in the southeast portion of the fire support base, assaulted and killed six NVA soldiers who were attempting to organize a strong point inside the perimeter. The cooks from India Battery accounted for 13 enemy killed when they manned a .50-caliber machine gun.

The defensive perimeter had been penetrated by several dozen sappers wearing only olive green shorts and skullcaps. They all carried packs full of explosives and were armed with shoulder-fired RPGs, satchel charges, bamboo mines, small arms and grenades.

The artillery battalion’s fire direction control center was put out of action, as was one howitzer. During the period from 4:10 a.m. to daylight only one of the Marines’ mortars remained in action. The mortar team stayed with their weapon throughout the assault, re-establishing communications with the commander in the fire direction control center and firing a total of 380 rounds.

Corporal Jim Best recalls the attack as a blur of indistinct memories. “There were red and green tracers flashing overhead, men screaming and explosions everywhere. I lay there hugging the ground thinking I may not get out, wondering if we’d been overrun.” Although penetrated, the Marine lines held and at times only a scant five feet separated the combating forces. Men not actively engaged in direct confrontations with the enemy forces were busy coordinating HEAT (high-explosive anti-tank) and illumination artillery fire or providing other support services. Artillery officers were coordinating fire missions while at the same time an air officer was on the radio requesting helicopter gunship support.

Lieutenant Raymond C. Benfatti, commanding officer of Company L, was severely wounded by an impacting rocket-propelled grenade during the initial moments of the attack. Ignoring his painful injuries, Benfatti steadfastly refused medical evacuation and boldly shouted words of encouragement to his men. He directed their fire against the infiltrating sappers and two supporting infantry companies until the hostile sapper unit was ejected from the perimeter.

Despite the enemy rounds impacting all around him, Lieutenant Benfatti quickly organized a reaction force and supervised his Marines in evacuating the casualties and replacing wounded Marines in defensive emplacements. As the enemy support units pressed their attack upon the perimeter, Benfatti continued his determined efforts, repeatedly exposing himself to intense hostile fire as he directed the efforts of his men in repulsing the enemy attack.

A flare ship was called on station to provide illumination outside the perimeter wire. It would remain on station throughout the night as the battle raged until dawn. With flares lighting up the night, a group of clerks, radio operators and engineers began a systematic drive to eliminate the enemy forces within the perimeter. Throughout the battle, Benfatti called for artillery fires from the batteries located on the mutually supporting firebases to surround FSB Cunningham in a curtain of hot steel. This supporting fire prevented enemy reinforcements and exploitation of breaches in the wire and also rendered impossible the retreat of the sappers already inside the compound.

At about 5:30 a.m. the Marines completed the reorganization of their positions and began slowly but methodically to break up the sapper attack. As Dawn broke, the spirited defenders were mopping up the remnants of the enemy assault force. Contact, however, was not broken until 7 a.m.

Jim Best described the end of the battle: “The fighting slowed and it was a few moments before I realized that the fire support base was dead silent. There were no sounds, only the fear of not knowing the exact situation.”

As the sun rose, the light and warmth it brought created a calming sense of temporary peace at FSB Cunningham. When it became apparent that the NVA had withdrawn for good, the counting began. Lieutenant Benfatti, who would win the Silver Star Medal for his actions during the attack, supervised the medical evacuation of casualties and ascertained the welfare of his Marines, resolutely refusing medical attention for his own wounds until all the other wounded men had been cared for.

The Marines found a total of 25 NVA bodies inside their defensive wires. One of those bodies was that of a sapper officer. Documents found on his body were examined, translated and analyzed by the 15th Interrogator/Translator Team, revealing the detailed planning of the attack described above.

“The use of narcotics,” platoon leader Milton J. Teixeira said, “mad them a lot harder to kill. Not one of the gooks we had inside the perimeter had less than three or four holes in him. Usually it took a grenade or something to stop him completely.”

A final tally of the battle damage revealed four Marines killed in action, 46 Marines wounded in action and 37 NVA killed in action. In “E” Battery, 2nd Battalion, 12 Marines, had taken heavy battle damage. Surveying the smoke-shrouded fire support base, Colonel Barrow said: “They’ll probably think twice from here on out before taking on another Marine headquarters group. These lads did a fantastic job in what could have been a nasty situation. They were 100 percent professional fighting men; good Marines all the way.”

This article was written by Michael R. Conroy and originally titled, “Sapper Attack in the A Shau”, and published in the August 1991 issue of VietnamMagazine.

I do have another article about FSB Cunningham and Sappers on this website. Click the following link to be redirected:

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I was on the 2nd CH-46 to sit down on what was called LZ India then changed to LZ Cunningham.. On the 3rd phase of the operation we were sent off from Cunningham a day before the others that had returned there to secure hill 1228 which was known as Tiger Mountain.. On our way there we spent most of the day we’d crossed the river engaged with the NVA.. The following day our point man was killed and we took a sporadic mortar fire until late afternoon.. After setting up a night position that evening the guys on our perimeter were detecting a lot of movement right before dark.. I requested a flare ship and was sent a Spooky gunship.. They determined that we were surrounded by a battalion sized unit and I started laughing.. Captain Arroyo asked what he saying and I told him He responded saying “that is good we can shoot in any direction and hit them. I was asked to mark the center most point in our perimeter and did so with a small orange strobe light and all hell broke out just outside of our position.. The following morning the guys manning lines watched the NVA drag off their dead and wounded and we moved out for 1228 when they were through.

Good read. Always interested to learn more about Operation Dewey Canyon. My brother was 9th Marines , 1st Lt. Robert Tim Rohweller and fought in this operation. Later killed by malcontents (fragged) in base camp.